/*
 * Licensed to Crate under one or more contributor license agreements.
 * See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership.  Crate licenses this file
 * to you under the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License.  You may
 * obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 * implied.  See the License for the specific language governing
 * permissions and limitations under the License.
 *
 * However, if you have executed another commercial license agreement
 * with Crate these terms will supersede the license and you may use the
 * software solely pursuant to the terms of the relevant commercial
 * agreement.
 */

package io.crate.metadata;

import org.elasticsearch.cluster.metadata.Metadata;
import org.elasticsearch.common.settings.Settings;

import java.util.Map;
import java.util.function.BiFunction;

/**
 * Marker interface for {@link Metadata.Custom} upgrade implementations.
 * All implementations will be loaded by a {@link java.util.ServiceLoader} and called
 * by the {@link org.elasticsearch.gateway.GatewayMetaState} to upgrade the custom meta data on node startup.
 */
@FunctionalInterface
public interface CustomMetadataUpgrader extends BiFunction<Settings, Map<String, Metadata.Custom>, Map<String, Metadata.Custom>> {
}
